Power delivery in a multiple-output system

ABSTRACT

The disclosed embodiments provide a system that operates a power supply. During operation, the system disposes a first switching mechanism between a first output of a first power converter and two or more loads. Next, the system obtains two or more error signals for the two or more loads, wherein each error signal from the two or more error signals represents a difference between a load voltage of a load from the two or more loads and a first reference voltage for the load from a first set of reference voltages for driving the two or more loads using the first power converter. The system then uses the first switching mechanism to couple the load with a largest error signal from the two or more error signals to the first output.

RELATED APPLICATION

This application claims the benefit of U.S. Provisional Application No.62/009,099, entitled “Power Delivery in a Multiple-Output System,” byinventor Louis Luh, filed 6 Jun. 2014, which is hereby incorporated byreference.

This application claims the benefit of U.S. Provisional Application No.62/042,608, entitled “Power Delivery in a Multiple-Output System,” byinventor Louis Luh, filed 27 Aug. 2014, which is hereby incorporated byreference.

The subject matter of this application is related to the subject matterin a non-provisional application by inventors Louis Luh, William C.Athas and Heather R. Sullens filed on the same day as the instantapplication, entitled “Reconfigurable Multiple-Output Power-DeliverySystem,” having Ser. No. 14/733,211, and filing date 8 Jun. 2015.

BACKGROUND

Field

The disclosed embodiments relate to power-delivery systems. Morespecifically, the disclosed embodiments relate to power delivery inmultiple-output systems.

Related Art

Often, power supplies for electronic devices such as smartphones, tabletcomputers, laptop computers, and desktop computers are designed toefficiently supply a wide range of power levels for a time-varying loadsuch as a central processing unit (CPU) or graphics processing unit(GPU). However, power supplies designed to work equally well over such awide range of power demands are typically not as efficient as powersupplies optimized to supply power over a narrow range of loads.Additionally, although the control logic for a power supply that candeliver power over a wide range of power demands may be stable at aconstant power level, transitioning between output power levels maycause decreased accuracy in the regulated output voltage.

Hence, the use of power supplies may be facilitated by improvementsrelated to their design and configuration.

SUMMARY

The disclosed embodiments provide a system that operates a power supply.During operation, the system disposes a first switching mechanismbetween a first output of a first power converter and two or more loads.Next, the system obtains two or more error signals for the two or moreloads, wherein each error signal from the two or more error signalsrepresents a difference between a load voltage of a load from the two ormore loads and a first reference voltage for the load from a first setof reference voltages for driving the two or more loads using the firstpower converter. The system then uses the first switching mechanism tocouple the load with a largest error signal from the two or more errorsignals to the first output.

In some embodiments, the system also generates a control signal forcontrolling an output current of the first power converter using alargest value of a half-wave-rectified error signal from the two or moreerror signals, a sum of positive error signals from the two or moreerror signals, and/or an on-duration of a logical disjunction signalgenerated from the two or more error signals.

In some embodiments, the output current is proportional to the controlsignal.

In some embodiments, the two or more error signals comprise two or morerequest signals obtained using two or more comparators.

In some embodiments, using the first switching mechanism to couple theload with the largest error signal to the first output comprisescoupling the first output to the load associated with a comparator fromthe two or more comparators that first asserts a request signalrepresenting a lower load voltage for the load than the referencevoltage for the load, and maintaining coupling of the first output tothe load for a minimum pre-specified time.

In some embodiments, the system also uncouples the first power converterfrom the two or more loads upon detecting a higher load voltage for eachload from the two or more loads than the first reference voltage fordriving the load from the two or more loads.

In some embodiments, the system also provides a second power converterwith a second output for driving at least one of the two or more loads.Upon detecting a lower load voltage of the load than a second referencevoltage for the load from a second set of reference voltages for drivingthe two or more loads using the second power converter, the systemengages the second power converter to supplement the lower load voltagewith an output voltage from the second output.

In some embodiments, the system also disposes a second switchingmechanism between the second output and the two or more loads, and usesthe second switching mechanism to couple the load with the largest errorsignal to the second output.

In some embodiments, the first power converter has a higher efficiencythan the second power converter, and the second power converter has ahigher power than the first power converter.

In some embodiments, a first switching frequency is used by the firstswitching mechanism to couple the load with the largest error signal tothe first output, and a second switching frequency that is higher thanthe first switching frequency is used by the second switching mechanismto couple the load with the largest error signal to the second output.

In some embodiments, the first reference voltage for driving the loadusing the first power converter is higher than the second referencevoltage for driving the load using the second power converter.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A shows a power supply in accordance with the disclosedembodiments.

FIG. 1B shows a power supply in accordance with the disclosedembodiments.

FIG. 2A shows a system for supplying power to components of a portableelectronic device in accordance with the disclosed embodiments.

FIG. 2B shows an exemplary voltage-based control circuit in accordancewith the disclosed embodiments.

FIG. 2C shows an exemplary voltage-based control circuit in accordancewith the disclosed embodiments.

FIG. 2D shows an exemplary voltage-based control circuit in accordancewith the disclosed embodiments.

FIG. 2E shows a state diagram for a finite state machine in a controlcircuit in accordance with the disclosed embodiments.

FIG. 3A shows a system for supplying power to components of a portableelectronic device in accordance with the disclosed embodiments.

FIG. 3B shows a control circuit in accordance with the disclosedembodiments.

FIG. 4A shows an exemplary power-delivery system in accordance with thedisclosed embodiments.

FIG. 4B shows an exemplary control circuit in accordance with thedisclosed embodiments.

FIG. 5A shows a power-delivery system in accordance with the disclosedembodiments.

FIG. 5B shows a power-delivery system in accordance with the disclosedembodiments.

FIG. 5C shows a power-delivery system in accordance with the disclosedembodiments.

FIG. 5D shows a power-delivery system in accordance with the disclosedembodiments.

FIG. 6 shows a flowchart illustrating the process of operating a powersupply in accordance with the disclosed embodiments.

FIG. 7A shows a power-delivery system in accordance with the disclosedembodiments.

FIG. 7B shows a power-delivery system in accordance with the disclosedembodiments.

FIG. 8A shows a power-delivery system in accordance with the disclosedembodiments.

FIG. 8B shows a power-delivery system in accordance with the disclosedembodiments.

FIG. 9 shows a flowchart illustrating the process of operating a powersupply in accordance with the disclosed embodiments.

FIG. 10A shows a flowchart illustrating the process of operating a powersupply in accordance with the disclosed embodiments.

FIG. 10B shows a flowchart illustrating the process of operating a powersupply in accordance with the disclosed embodiments.

FIG. 11 shows a portable electronic device in accordance with thedisclosed embodiments.

In the figures, like reference numerals refer to the same figureelements.

DETAILED DESCRIPTION

The following description is presented to enable any person skilled inthe art to make and use the embodiments, and is provided in the contextof a particular application and its requirements. Various modificationsto the disclosed embodiments will be readily apparent to those skilledin the art, and the general principles defined herein may be applied toother embodiments and applications without departing from the spirit andscope of the present disclosure. Thus, the present invention is notlimited to the embodiments shown, but is to be accorded the widest scopeconsistent with the principles and features disclosed herein.

The data structures and code described in this detailed description aretypically stored on a computer-readable storage medium, which may be anydevice or medium that can store code and/or data for use by a computersystem. The computer-readable storage medium includes, but is notlimited to, volatile memory, non-volatile memory, magnetic and opticalstorage devices such as disk drives, magnetic tape, CDs (compact discs),DVDs (digital versatile discs or digital video discs), or other mediacapable of storing code and/or data now known or later developed.

The methods and processes described in the detailed description sectioncan be embodied as code and/or data, which can be stored in acomputer-readable storage medium as described above. When a computersystem reads and executes the code and/or data stored on thecomputer-readable storage medium, the computer system performs themethods and processes embodied as data structures and code and storedwithin the computer-readable storage medium.

Furthermore, methods and processes described herein can be included inhardware modules or apparatus. These modules or apparatus may include,but are not limited to, an application-specific integrated circuit(ASIC) chip, a field-programmable gate array (FPGA), a dedicated orshared processor that executes a particular software module or a pieceof code at a particular time, and/or other programmable-logic devicesnow known or later developed. When the hardware modules or apparatus areactivated, they perform the methods and processes included within them.

The disclosed embodiments provide a power supply for an electronicdevice. As shown in FIG. 1A, the power supply 100 includes a powersource 110 and one or more power converters 120. Power converters 120may obtain an input voltage or current from power source 110 and convertthe input voltage or current into a number of output voltages orcurrents for use by a number of loads 122-128 in the electronic device.For example, power converters 120 may convert direct current (DC) powerfrom a power adapter acting as power source 110 into low-voltage directcurrent (DC) that is used to charge a battery and/or power components ofa portable electronic device such as a mobile phone, laptop computer,portable media player, and/or tablet computer. When multiple DC powersources are present (e.g., from a power adapter and an externalbattery), current may be supplied from either or both power sourcesdepending on a number of factors, such as available current from thepower adapter. In another example, power source 110 may further includethe battery or battery pack in the portable electronic device, such as alithium-ion and/or lithium-polymer battery pack. Thus, power converters120 may include buck converters, boost converters, buck-boostconverters, single-ended primary-inductor converters (SEPICs), Ćukconverters, and/or class-E DC/DC converters. Power converters 120—mayalso be configured to convert from alternating current (AC) power to DCpower, AC to AC, DC to DC, and DC to AC depending on the types of powerprovided by power source 110 and/or used by loads 122-128.

In one or more embodiments, power supply 100 delivers power to multipleindependent loads (e.g., loads 122-128) in a portable electronic devicesuch as a laptop computer, tablet computer, mobile phone, personaldigital assistant (PDA), portable media player, and/or digital camera.Each load may include one or more components, which are poweredseparately from the component(s) in other loads of the portableelectronic device. For example, loads 122-128 may include the centralprocessing unit (CPU), graphics-processing unit (GPU), memory,integrated circuits, radio, ports, and/or other components in theportable electronic device. The components may be grouped into differentloads 122-128 based on the voltage, current, and/or power requirementsor consumption of the components.

In other words, power supply 100 may include functionality to deliverpower to a multiple-output system (e.g., for driving multiple loads122-128) using one or more power converters 120. More generally, asshown in FIG. 1B, power converters 120 may be coupled to multiple loads124-126 through a switching assembly 130 containing one or moreswitches. As discussed below, loads 124-126 may be individually coupledto one or more power converters 120, or multiple power converters 120may be combined into a single output that is used to power multipleloads 124-126. Each load may be coupled to a feedback unit (e.g.,feedback units 134-136) that monitors the current, voltage, and/or otheraspects of the load. The monitored information may be provided byfeedback units 134-136 as feedback signals to a control unit 140 thatoperates power converters 120 and switching assembly 130 based at leastin part on the feedback signals.

As shown in FIG. 2A, an input voltage (e.g., “V_(IN)”) is supplied froma power source 200 such as a battery for a portable electronic deviceand/or a power adapter. The input voltage may be converted into two loadvoltages (e.g., “V_(DD1)” and “V_(DD2)”) for driving two loads 206-208respectively using a control circuit 202, a voltage regulator 204 and/orother type of power converter, and a switching mechanism 210.Consequently, the circuit of FIG. 2A may provide a single-input,multiple-output (SIMO) power supply with one input voltage and twooutput and/or load voltages.

More specifically, an input of voltage regulator 204 is coupled to theinput voltage, and loads 206-208 are alternately coupled to an output(e.g., “p_out”) of voltage regulator 204 via switching mechanism 210.Control circuit 202 may generate a switching signal (e.g., “SW”) thatcontrols switching mechanism 210 to switch the output of voltageregulator 204 to either load 206-208, depending on the power consumptionof loads 206-208. For example, control circuit 202 may use the loadvoltages of loads 206-208 as feedback voltages (e.g., “V_(FB1)” and“V_(FB2)”) that are supplied as feedback signals for controllingswitching mechanism 210. Control circuit 202 may further use the loadvoltages to generate a first control signal (e.g., “EN”) to turn voltageregulator 204 on or off and a second control signal (e.g., “Ctrl”) tocontrol the output current of voltage regulator 204. In some instances,switching mechanism 210 may be configured to connect the output ofvoltage regulator 204 to both loads 206-208 at the same time in a “tied”configuration, as discussed in further detail below with respect toFIGS. 8A-8B.

As shown in FIG. 2B, an exemplary implementation of control circuit 202that is compatible with the power-delivery system of FIG. 2A may includetwo error amplifiers 212-214 that generate two error signals such aserror voltages (e.g., “V_(ERR1)” and “V_(ERR2)”) from the feedbackvoltages of loads 206-208 and two reference voltages (e.g., “V_(REF1)”and “V_(REF2)”), respectively. Each reference voltage may represent atarget value for the feedback voltage of the corresponding load 206-208.In turn, each error signal may represent the difference between thereference voltage and the load voltage of the load. For example, theerror signal may be calculated by subtracting the feedback voltage ofthe load from the reference voltage for the load. As a result, the errorsignal may be negative when the load voltage is higher than thereference voltage and positive when the load voltage is lower than thereference voltage. Alternatively, error signals may be generated fromreference and/or load currents instead of voltages.

Moreover, the gains of error amplifiers 212-214 may be selected to bedifferent to increase the sensitivity to error of one load over that ofthe other load. For example, error amplifier 212 may have a higher gainthan error amplifier 214 to prioritize driving of the load associatedwith the error signal from error amplifier 212 (i.e., load 206) overdriving of the load associated with the error signal from erroramplifier 214 (i.e., load 208).

The error signals from error amplifiers 212-214 may be provided to threecomparators 216-220 in control circuit 202. Comparator 220 may determinewhich error signal is larger, comparator 216 may determine if the errorsignal from error amplifier 212 is positive, and comparator 218 maydetermine if the error signal from error amplifier 214 is positive. Apositive value for a given error signal may indicate that the loadvoltage of the corresponding load is lower than its reference voltage.The outputs of comparators 216-220 are then provided as inputs to twoAND gates 222-224 and/or an OR gate 226.

OR gate 226 is coupled to the outputs of comparators 216-218 andgenerates the control signal (e.g., “EN”) for turning voltage regulator204 on if either error signal is positive. If both error signals arenegative (e.g., if each load has a higher load voltage than thecorresponding reference voltage), OR gate 226 may use the control signalto turn voltage regulator 204 off.

AND gates 222-224 are coupled to the output of comparator 220, AND gate222 is coupled to the output of comparator 216, and AND gate 224 iscoupled to the output comparator 218. AND gates 222-224 may use theoutputs of comparators 216-220 to generate switch control signals (e.g.,“SW1_ON,” “SW2_ON”) for operating switches (e.g., “SW1,” “SW2”) coupledto the outputs of error amplifiers 212-214, respectively. In turn, theswitches may couple one of the error signals to the control signal(e.g., “Ctrl”) for controlling the output current of voltage regulator204. In other words, AND gates 222-224 may provide an analog multiplexerthat selects one of the two error signals to pass to voltage regulator204 for controlling the output of voltage regulator 204. The switchcontrol signals may also be used to control switching mechanism 210. Forexample, the “SW1_ON” signal may be used as the “SW” signal in FIG. 2Athat controls switching mechanism 210 so that switching mechanism 210couples voltage regulator 204 to load 206 when switch SW1 is closed andto load 208 when switch SW1 is open. Conversely, the switch controlsignals for the “SW1” and “SW2” switches in control circuit 202 may begenerated separately from the “SW” signal for controlling switchingmechanism 210.

Another control scheme for generating the control signal (e.g., “Ctrl”)is shown in FIG. 2C. In FIG. 2C, the control signal may be generated asthe sum of two half-wave-rectified error voltages from two rectifiers230-232. That is, rectifiers 230-232 may rectify the error voltages fromerror amplifiers 212-214, respectively, by outputting the positiveportions of the error voltages and setting the negative portions to 0. Apositive error voltage may indicate a feedback voltage that is lowerthan the corresponding reference voltage, while a negative error voltagethat is negative may represent a feedback voltage that is higher thanthe corresponding reference voltage. Thus, the positive error voltagemay be reduced by supplying power from voltage regulator 204 to thecorresponding load, while the negative error voltage may be reduced byreducing or removing the supply of power from voltage regulator 204 tothe corresponding load. The rectified error voltages may then be summedby a voltage-summation circuit 234 as the control signal.

The control signal (e.g., “Ctrl”) may be used to control the pulse-widthmodulation (PWM) of a switching waveform for controlling a switchingvoltage regulator 204 and/or as a peak current control for peakcurrent-mode control of voltage regulator 204. For example, the controlsignal may provide the largest value of the half-wave-rectified errorvoltages (e.g., the error voltage with a positive value) to voltageregulator 204 so that voltage regulator 204 generates an output currentthat is proportional to the largest error signal.

To reduce the operating power of the regulator, the control circuit 202may be implemented without error amplifiers, as shown in FIG. 2D.Comparators 216 and 218 may compare the feedback signals (e.g.,“V_(FB1)” and “V_(FB2)”) representing the load voltages of loads 206-208with the corresponding reference voltages (e.g., “V_(REF1)” and“V_(REF2)”) to generate request signals corresponding to error signals.The outputs of comparators 216-218 (e.g., the request signals) areprovided to OR gate 226 to generate a logical disjunction signal thatacts as control signals (e.g., “Ctrl” and “EN”) for enabling voltageregulator 204 and controlling the output current of voltage regulator204. Voltage regulator 204 may use the continuous-on duration of thelogical disjunction signal to control the PWM, the peak current, and/orthe current slope of voltage regulator 204.

The switching control for switching mechanism 210 may additionally beimplemented as a first-come, first-served switching control using afinite state machine 236 in control circuit 202. The operation of finitestate machine 236 is shown in FIG. 2E. Finite state machine 236 mayinclude a first step (e.g., “STEP 1”), in which finite state machine 236is in an initialization state 240 (e.g., “INIT”), and switchingmechanism 210 couples the output of voltage regulator 204 to either ofthe loads 206-208.

Finite state machine 236 may also include a second step (e.g., “STEP 2”)that allows a first of comparators 216-218 to assert a positive output(e.g., indicating that the load voltage of the corresponding load islower than the reference voltage for the load) to cause switchingmechanism 210 to couple to the corresponding load 206-208 for a minimumpre-specified time X (e.g., a number of microseconds). If comparator 216asserts first without comparator 218 simultaneously asserting (e.g.,“Comp 216=1, Comp 218 !=1”), finite state machine 236 may enter state242 (e.g., “HOLD 1”), which generates a control signal (e.g.,“SW1_ON=1”) that causes switching mechanism 210 to couple the output ofvoltage regulator 204 to load 206. If comparator 218 asserts first(e.g., “Comp 218=1”) with or without comparator 216 simultaneouslyasserting, finite state machine 236 may enter state 244 (e.g., “HOLD2”), which generates a control signal (e.g., “SW2_ON=1”) that causesswitching mechanism 210 to couple the output of voltage regulator 204 toload 208. As a result, finite state machine 236 may enter state 242 onlywhen comparator 216 asserts first and state 244 both when comparator 218asserts first and both comparators 216-218 assert at the same time.During the time interval X, no switching is allowed and comparator206-208 signals are ignored.

Finite state machine 236 may include a third step (e.g., “STEP 3”) thatoccurs after the time interval X has elapsed. In the third step,switching mechanism 210 may remain in the same configuration until thecorresponding comparator 216-218 is de-asserted and the other comparatoris asserted. To this end, finite state machine 236 may enter a state246-248 (e.g., “ACTIVE 1” or “ACTIVE 2”) that maintains theconfiguration of switching mechanism 210. That is, finite state machine236 may remain in state 246 while comparator 216 is asserted andcomparator 218 is de-asserted (e.g., “Comp 216 !=0, Comp 218 !=1).Similarly, finite state machine 236 may remain in state 238 whilecomparator 218 is asserted and comparator 216 is de-asserted (e.g.,“Comp 216 !=1, Comp 218 !=0). If the comparator associated with thestate (e.g., state 246 or 248) de-asserts and the other comparator has apositive output, finite state machine 236 may go back to the second stepand enter a state (e.g., state 242 or 244) that configures switchingmechanism 210 to couple the output of voltage regulator 204 to the otherload. For example, finite state machine 236 may remain in state 248while comparator 218 is asserted and comparator 216 is de-asserted. Whencomparator 216 asserts and comparator 218 de-asserts, finite statemachine 236 may transition to state 242. If both comparators arede-asserted, both finite state machine 236 and switching mechanism 210may remain the same state and/or configuration until one comparator216-218 has a positive output and triggers a switch back to a state inthe second step.

The error signals may further be used by control circuit 202 to coupleloads 206-208 to voltage regulator 204. In particular, control circuit202 may use switching mechanism 210 to couple the load with the largesterror signal to the output of voltage regulator 204, thereby allowingthe load to be driven by the output. As the coupled load is driven bythe output according to the error signal for the coupled load, the loadvoltage of the other load may fall until the other load has a largererror signal than the coupled load. Control circuit 202 may then useswitching mechanism 210 to couple the other load to the output ofvoltage regulator 204 and provide the error signal of the other load tovoltage regulator 204 so that voltage regulator 204 generates anappropriate output current for driving the other load.

Consequently, implementations of control circuit 202 in FIGS. 2B-2D maycontinuously switch between driving loads 206-208 using voltageregulator 204 and switching mechanism 210. As one load “charges” upusing the output of voltage regulator 204, the load voltage of the otherload drops until the error signal of the other load is larger, causingcontrol circuit 202 to switch to charging the other load with the outputof voltage regulator 204. Control circuit 202 may thus use feedbackloops, switching mechanism 210, and a single voltage regulator 204 toregulate the load voltages of loads 206-208 to be at the correspondingreference voltages for loads 206-208.

Such power-delivery techniques may also be applied to multiple-input,multiple-output (MIMO) systems. As shown in FIG. 3A, an input voltage(e.g., “V_(IN)”) is supplied from a power source 300 and converted intotwo load voltages (e.g., “V_(DD1)” and “V_(DD2)”) for driving two loads308-310 using a control circuit 302, two voltage regulators 304-306, andtwo switching mechanisms 312-314. The power supply of FIG. 3A may thusbe a 2-in 2-out MIMO system.

In particular, the inputs of voltage regulators 304-306 are coupled tothe input voltage, and loads 308-310 are selectively coupled to anoutput (e.g., “p_out1”) of voltage regulator 304 using switchingmechanism 312 and an output (e.g., “p_out2”) of voltage regulator 306using switching mechanism 314. At any given moment, voltage regulators304-306 may be connected to the same load or to different loads.Although the power-delivery system of FIG. 3A is illustrated withvoltage regulators 304-306, those skilled in the art will appreciatethat the power-delivery system may utilize any suitable powerconverters, such as the power converters discussed above.

As with control circuit 202 of FIGS. 2A-2B, control circuit 302 may useswitching mechanisms 312-314 to switch the outputs of voltage regulators304-306 to either load 308-310, depending on the power consumption ofloads 308-310. For example, control circuit 302 may use the loadvoltages of loads 308-310 as feedback voltages (e.g., “V_(FB1)” and“V_(FB2)”) for: controlling switching mechanisms 312-314, generating afirst set of control signals (e.g., “EN1,” “EN2”) for turning voltageregulators 304-306 on or off, and generating a second set of controlsignals (e.g., “Ctrl1,” “Ctrl2”) for controlling the output currents ofvoltage regulators 304-306. Each control signal may be used to controlthe operation and/or output of the corresponding voltage regulator. Forexample, “EN1” may be used to turn voltage regulator 304 on and off,“Ctrl1” may be used to control the output current of voltage regulator304, “EN2” may be used to turn voltage regulator 306 on and off, and“Ctrl2” may be used to control the output current of voltage regulator306.

In one or more embodiments, voltage regulators 304-306 include ahigher-efficiency, lower-power regulator and a higher-power,lower-efficiency regulator. To facilitate efficient operation of thepower supply, the higher-efficiency regulator may be used as a primaryvoltage regulator for driving loads 308-310, and the higher-powerregulator may be turned on only when more power than thehigher-efficiency regulator can deliver is required by one or both loads308-310.

As shown in FIG. 3B, one example of control circuit 302 suitable for usein the system of FIG. 3A includes two sub-circuits 320-322, with eachsub-circuit used to independently control a different voltage regulator304-306 and switching mechanism 312-314 coupled to the voltageregulator. Each sub-circuit 320-322 may include the components ofvarious examples of control circuit 202 in FIGS. 2A-2D. Each sub-circuitmay generate error signals based on a comparison of feedback voltagesand corresponding reference voltages (e.g., using error amplifiers asdiscussed with respect to FIGS. 2B-2D). For example, sub-circuits320-322 may each include two error amplifiers that generate errorsignals (e.g., error voltages) for loads 308-310 from the load and/orfeedback voltages of loads 308-310 (e.g., “V_(FB1)” and “V_(FB2)”) andreference voltages (e.g., “V_(REF1),” “V_(REF2),” “V_(REF1)+x,”“V_(REF2)+x”) for driving the loads using each voltage regulator304-306. Each sub-circuit 320-322 may also include three comparatorsthat identify the larger error signal from loads 308-310 and indicatewhether the load voltages of loads 308-310 are lower than theirreference voltages. Finally, each sub-circuit 320-322 may include an ORgate that generates a control signal (e.g., “EN1,” “EN2”) for turningthe corresponding voltage regulator 304-306 on and off, as well as twoAND gates that generate switch control signals (e.g., “SW1_1,” “SW1_2,”“SW2_1,” “SW2_2”) for operating switches that couple the larger errorsignal to a control signal (e.g., “Ctrl1,” “Ctrl2”) for controlling theoutput current of the voltage regulator.

Each of sub-circuits 320-322 may additionally use the error signals andswitching mechanisms 312-314 to couple the load with the largest errorsignal to the voltage regulators corresponding to the sub-circuit.Consequently, sub-circuits 320-322 may each be a SIMO control circuitthat is included in control circuit 302 to enable control of a MIMOpower-delivery system.

In addition, the reference voltages used with sub-circuit 320 (e.g.,“V_(REF1)+x,” “V_(REF2)+x”) may be higher than the reference voltagesused with sub-circuit 322 (e.g., “V_(REF1),” “V_(REF2)”). For example,the reference voltages used with sub-circuit 320 may be a predeterminedamount (e.g. 10 mV) higher than the reference voltages used withsub-circuit 322. By setting higher reference voltages for use bysub-circuit 320, control circuit 302 may increase the use of the voltageregulator (e.g., a higher-efficiency, lower-power regulator) controlledby sub-circuit 320 over the use of the voltage regulator (e.g., ahigher-power, lower-efficiency regulator) controlled by sub-circuit 322in driving loads 308-310.

More specifically, the higher reference voltages used by sub-circuit 322may allow a higher-efficiency voltage regulator controlled bysub-circuit 320 to be used in driving loads 308-310 by outputtingvoltages to loads 308-310 that are regulated to be at the higherreference voltages. Since the higher reference voltages are above thereference voltages of sub-circuit 322, sub-circuit 322 may generate acontrol signal (e.g., “EN2”) that turns off a higher-power voltageregulator controlled by sub-circuit 322. However, when one or both loads308-310 draw power at a level above the power limit of thehigher-efficiency voltage regulator controlled by sub-circuit 320, thepower demands of the load(s) may exceed the power limit of thehigher-efficiency voltage converter, causing the load voltage(s) of theload(s) to decrease. Once the load voltage(s) decrease to at or belowthe reference voltage(s) of sub-circuit 322, sub-circuit 322 may engage(e.g., turn on) the higher-power voltage regulator and use an outputvoltage from the output of the higher-power voltage regulator tosupplement the lowered load voltage(s). When the higher-power voltageregulator is not used to supplement the load voltage(s), thehigher-power voltage regulator may be placed in a power savings standbymode.

The efficiency and/or transient response of the power-delivery systemmay further be improved by using different maximum switching frequenciesto drive loads 308-310. For example, sub-circuit 320 may use a firstmaximum switching frequency (e.g., 400 KHz) to couple the load with thelargest error signal to the output of the higher-efficiency regulator,while sub-circuit 322 may use a second maximum switching frequency thatis higher than the first switching frequency (e.g., 2 MHz) to couple theload with the largest error signal to the output of the higher-powerregulator. The maximum switching frequency of each sub-circuit may belimited using a clock signal and/or a minimum dwell time (e.g., timeinterval X in finite state machine 236 of FIGS. 2D-2E). The lowermaximum switching frequency of sub-circuit 320 may improve theefficiency of the higher-efficiency regulator, while the higher maximumswitching frequency of sub-circuit 322 may improve the transientresponse of the higher-power regulator. Alternatively, the operation ofsub-circuits 320-322, components within sub-circuits 320-322, and/orswitching mechanisms 312-314 may be asynchronous.

FIG. 4A shows an exemplary power-delivery system in accordance with thedisclosed embodiments. More specifically, FIG. 4A shows a 2-in 4-outMIMO power-delivery system with a set of simulation settings. Similarly,FIG. 4B shows a control circuit for the simulated MIMO power-deliverysystem of FIG. 4A.

The MIMO power-delivery system of FIG. 4A includes two buck converters402-404 and load voltages 406-412 of four different loads (e.g.,“Load1,” “Load2,” “Load3,” “Load4”). One buck converter 404 is ahigh-efficiency converter for regulating power (e.g., maintaining loadvoltages) during normal and/or light-load conditions, and the other buckconverter 402 is a high-power converter for driving high loads and/ortransient conditions. An input voltage is supplied to buck converters402-404 from a power source 414 such as a battery pack.

Converter 402 may be coupled to the loads using a switching mechanism416, and converter 404 may be coupled to the loads using a separateswitching mechanism 418. Reference voltages for driving the “Load1,”“Load2,” “Load3,” and “Load4” loads using the high-power converter 402may be set to 5V, 12V, 3.3V, and 1V, respectively, in switchingmechanism 416. Reference voltages for driving the “Load1,” “Load2,”“Load3,” and “Load4” loads using the high-efficiency converter 404 maybe set to slightly higher values of 5.01V, 12.01V, 3.31V, and 1.01V,respectively, in switching mechanism 418. Both buck converters 402-404may be controlled using constant on-time peak current control. Thehigh-efficiency converter 404 may have an inductor 422 with aninductance of 2.2 uH, a peak output current of 1 A, and a switchingspeed of 400 KHz provided by a clock 426. The high-power converter 402may have an inductor 420 with an inductance of 200 nH, a peak outputcurrent of 10 A, and a switching speed of 2 MHz provided by a separateclock 424. The reference voltage used with the high-efficiency converter404 may be 10 mV higher than the reference voltage used with thehigh-power converter 402.

Alternative configurations of inputs and outputs in the power-deliverysystem are shown in FIGS. 5A-5D. In particular, FIG. 5A shows threepower converters coupled to two loads 508-510. One or morehigh-efficiency converters 506 may be selectively coupled to one or bothloads 508-510 using a switching assembly 512, and a dedicated high-powerconverter 502-504 is coupled to each load 508-510.

The shared high-efficiency converters 506 may be switched or sharedbetween the two loads 508-510 based on the power demands of loads508-510. For example, switching assembly 512 may couple a singlehigh-efficiency converter to the load from loads 508-510 with thehighest need, which may be represented by the difference between thereference voltage for driving the load using high-efficiency converter506 and a load voltage of the load. If the power-delivery systemincludes multiple high-efficiency converters 506, switching assembly 512may divide high-efficiency converters 506 between loads 508-510depending on need by, for example, allocating more converters to theload with the higher demand. High-power converters 502-504 may also beassociated with a higher activation threshold than high-efficiencyconverters 506 to facilitate efficient operation of the power supply.For example, the reference voltages of high-efficiency converters 506may be slightly higher than the reference voltages of high-powerconverters 502-504 to enable use of high-efficiency converters 506during normal, light-load conditions. Each high-power converter 502-504may then be engaged and used to supplement the output of high-efficiencyconverter 506 once the power demands of the corresponding load cause theload voltage of the load to drop below the reference voltage of thehigh-power converter.

FIG. 5B also shows three power converters coupled to two loads 520-522.In the configuration of FIG. 5B, a dedicated high-efficiency converter514-516 is coupled to each load 520-522, and one or more high-powerconverters 518 are shared by loads 520-522 using a switching assembly524. As with switching assembly 512 of FIG. 5A, switching assembly 524may divide multiple high-power converters 518 between loads 520-522depending on need, or switching assembly 524 may allocate a singlehigh-power converter to the load with the higher demand. High-powerconverter 518 may be used to drive one or both loads 520-522 only whenthe power demands of the load(s) exceed the power limits of thecorresponding dedicated high-efficiency converter(s) and cause the loadvoltage(s) of the load(s) to drop below the reference voltage ofhigh-power converter 518.

FIG. 5C shows a number of power converters 526-528 and two loads530-532. One power converter 526 is a dedicated power converter that isdirectly coupled to a first load 530, while one or more additional powerconverter 528 are shared between the first load and a second load 532using a switching assembly 534 according to the needs of loads 530-532.

FIG. 5D shows a number of power converters and two loads 542-544. One ormore high-power converters 536 and one or more high-efficiencyconverters 538 are shared by both loads using two switching assemblies546-548, and a third dedicated power converter 540 is coupled directlyto the second load 544.

FIG. 6 shows a flowchart illustrating the process of operating a powersupply in accordance with the disclosed embodiments. In one or moreembodiments, one or more of the steps may be omitted, repeated, and/orperformed in a different order. Accordingly, the specific arrangement ofsteps shown in FIG. 6 should not be construed as limiting the scope ofthe embodiments.

Initially, two or more error signals for two or more loads coupled tothe output(s) of one or more power converters via one or more switchingmechanisms are obtained (operation 602). For example, the switchingmechanisms may be disposed between the outputs of one or more voltageregulator and the loads. As a result, the voltage regulator(s) may becontrolled in a group so that all voltage regulators in the group arecoupled to a given load at the same time.

The error signals may be provided by two or more error amplifiers and/orcomparators. Each error signal may be an error voltage that representsthe difference between a reference voltage for driving a load from thetwo or more loads using a voltage regulator and a load voltage of theload. For example, the error signal may include an analog error voltagegenerated by an error amplifier and/or a digital request signalgenerated by a comparator. As a result, a reference voltage may be setfor each load and each voltage regulator that may be used to drive theload. Each reference voltage may represent a constant target regulatedoutput voltage of the corresponding load. The error signal may thus bepositive if the load voltage is lower than the reference voltage andnegative if the load voltage is higher than the reference voltage.

Next, the error signals may be used to determine if the load voltagesare higher than the corresponding reference voltages (operation 604) foreach power converter or group of power converters that are collectivelycoupled to one of the loads. If all load voltages are higher than theircorresponding reference voltages, the power converter(s) that can beselectively coupled to the loads are turned off (operation 606). Forexample, a high-power voltage regulator may be turned off if the loadvoltages of the corresponding loads are regulated to be at the referencevoltage(s) of a high-efficiency voltage regulator, which is higher thanthe reference voltage(s) of the high-power voltage regulator.

If one or more load voltages are lower than the corresponding referencevoltages, one or more switching mechanism(s) may be used to couple theload with the largest error signal to one or more outputs of one or morepower converters (operation 608). For example, an output of a voltageregulator may be coupled to the load associated with a comparator thatfirst signals a request signal representing a lower load voltage for theload than the reference voltage for the load. Coupling of the output tothe load may also be maintained for a minimum pre-specified time. Suchcoupling of the output to the load may continue until the comparator nolonger asserts a lower load voltage for the reference voltage andanother comparator associated with the voltage regulator signals aseparate request signal representing a lower load voltage for the loadassociated with the comparator than the load's reference voltage.

Alternatively, no switching mechanism may be required to couple the loadto an output of a power converter (e.g., a dedicated voltage regulator)if the load is connected directly to the output. In addition, a controlsignal for controlling an output current of each coupled power convertermay be generated (operation 610). The control signal may be generatedusing the largest value of a half-wave-rectified error signal (e.g., thepositive portion of the error signal) from the two or more errorsignals, the sum of positive error signals, and/or an on-duration of alogical disjunction signal generated from the error signals. Inaddition, the output current may be generated by each coupled powerconverter to be proportional to the corresponding control signal.

The loads may continue to be driven (operation 612) using the switchingmechanism(s) and power converter(s). If the loads are to be driven,error signals for the loads are periodically and/or continuouslyobtained (operation 604) and used to operate the power converter(s)and/or couple the power converter(s) to the loads (operations 604-610).The operations in the flowchart of FIG. 6 may also be repeated for eachgroup of commonly controlled power converters, such as groups of one ormore power converters coupled to individual sub-circuits (e.g.,sub-circuits 320-322 of FIG. 3B) of a control circuit (e.g., controlcircuit 302 of FIGS. 3A-3B) in the power supply. Voltages and currentsmay continue to be supplied to the loads by the power converter(s) untilthe power supply is no longer used to drive the loads.

In one or more embodiments, a MIMO power-delivery system such as thepower-delivery systems of FIGS. 3A, 4A, and 5A-5D may be configuredthrough a software-based control apparatus. As shown in FIG. 7A, theoutputs of a number of power converters 702-710 may be coupled to two ormore loads 714-716 through a switching assembly 712 comprising one ormore switching mechanisms. A control apparatus 718 (which may beexecuting within a load, e.g., load 714) may be used to generate controlsignals for switching assembly 712 so that power converters 702-710 arecoupled to loads 714-716 through switching assembly 712 in variousconfigurations. For example, control apparatus 718 may be a softwarecomponent that executes within an operating system and/or systemmicrocontroller (SMC) of a portable electronic device. The softwarecomponent may monitor conditions in loads 714-716 and generate controlsignals for controlling an actively controlled switching assembly 712that includes switching mechanisms such as powermetal-oxide-semiconductor field-effect transistors (MOSFETs).

More specifically, the output of one or more power converters (e.g.,power converter 702) may be coupled directly to load 714, and the outputof one or more power converters (e.g., power converter 710) may becoupled directly to load 716. Power converters 704-708 may individuallybe coupled to either load 714-716 through switching assembly 712 thatare controlled by control apparatus 718.

In some instances, control apparatus 718 may be used to configure thedelivery of power from power converters 702-710 to loads 714-716 thatare capable of drawing, in aggregate, power that exceeds thepower-output capabilities of power converters 702-710. For example,power converters 702-710 may each be 3 W step-down buck regulators in aspace-limited portable electronic device, while each load 714-716 in theportable electronic device may draw up to 10 W of power. Thus, themaximum power that can be drawn by both loads 714-716 is 20 W, whichexceeds the maximum of 15 W that can be delivered by power converters702-710.

In these instances, the total amount of power drawn by both loads714-716 may be limited to the maximum that can be supplied by powerconverters 702-710. Continuing with the above example, loads 714-716 maybe prevented from drawing the maximum 10 W of power at the same timebecause power converters 702-710 cannot supply 20 W of power to loads714-716.

In one or more embodiments, control apparatus 718 may manage thedelivery of power from power converters 702-710 to loads 714-716 basedon discrete, pre-defined power states of loads 714-716. The power statesmay be represented by different power supply voltage and clock frequencycombinations in the portable electronic device. For example, the powerstates of one or both loads 714-716 may be represented by monotonicallyincreasing numbers from 0 to N with increasing power demands (e.g.,power supply voltage VDD and clock frequency F_(CLK)). The power staterepresented by 0 may be the lowest power state, which is used duringidle periods in the portable electronic device. The power staterepresented by N may be the highest power state, which is used tomaximize computing power on the portable electronic device. Power statesrepresented by 1 through N-1 may be selected based on the computingdemands of applications and/or components on the portable electronicdevice.

Since the power demand of loads 714-716 may be directly related to thepower states of loads 714-716, control apparatus 718 may dynamicallyconfigure the coupling of power converters 702-710 to loads 714-716based on the power states. In general, control apparatus 718 mayconfigure the coupling of at least one power converter and up to fourpower converters to each load 714-716, with more power convertersassigned to the load with the higher power state. For example, anoperating system on the portable electronic device may determine thepower states of loads 714-716 and execute control apparatus 718 togenerate control signals for configuring the power-delivery system basedon the power states and/or a power-delivery policy for the portableelectronic device.

Using the exemplary monotonically increasing power states of 0 through9, control apparatus 718 may configure the coupling of loads 714-716 topower converters 702-710 through switching assembly 712 using thefollowing exemplary power-delivery policy:

-   -   1. If the power state of a first load increases from less than 2        to 2 or 3 and the power state of the second load is lower than        6, the first load will be coupled to two power converters if the        first load is currently coupled to only one power converter.    -   2. If the power state of the first load increases from less than        4 to 4 or 5 and the power state of the second load is lower than        4, the first load will be coupled to three power converters if        the first load is currently coupled to fewer than three power        converters.    -   3. If the power state of the first load increases from less than        6 to 6 or 7 and the power state of the second load is lower than        2, the first load will be coupled to four power converters if        the first load is currently coupled to fewer than four power        converters.        The power-delivery policy may thus specify an increase in the        number of power converters coupled to a given load when the        power state of the load increases above a first threshold and/or        the power state of the other load remains below a second        threshold. On the other hand, if an increase in the power state        of the load does not exceed the first threshold, the        power-delivery policy may maintain an existing configuration of        the coupling of loads 714-716 to power converters 702-710        through switching assembly 712 to avert unnecessary power        dissipation associated with reconfiguring switching assembly        712.

Those skilled in the art will appreciate that the exemplarypower-delivery policy described above may be used to couple loads714-716 to power converters 702-710 as long as the maximum power demandfrom both loads does not exceed the 15 W that can be supplied by allfive power converters 702-710. If the power demanded by loads 714-716exceeds the maximum that can be generated by power converters 702-710,one or both loads may experience voltage droops, current surges, and/orpower overages.

As shown in FIG. 7B, the desired power states and/or power demands ofloads 714-716 may be monitored by a number of digital-to-analogconverters (DACs) 724-726 and comparators 720-722 that are added to thepower-delivery system of FIG. 7A. Comparator 720 may compare the loadvoltage of load 714 with a reference voltage for driving load 714 fromDAC 724 to detect a droop in the load voltage of load 714. Similarly,comparator 722 may compare the load voltage of load 716 with a referencevoltage for driving load 716 from DAC 726 to detect a droop in the loadvoltage of load 716.

Control apparatus 718 may monitor the voltage droops of loads 714-716from comparators 720-722 and generate control signals for controllingswitching assembly 712 and/or the power states of loads 714-716 based onthe monitored voltage droopss, current surges, and/or power overages. Ifthe load voltage of a first load is lower than the correspondingreference voltage by more than a given amount (e.g., 50 mV), controlapparatus 718 may generate a control signal to change a coupling of oneor more additional power converters from a second load to the firstload. Control apparatus 718 may also reduce a power state of the firstload, in lieu of or in addition to diverting the additional powerconverters from the second load to the first load.

For example, control apparatus 718 may divert power converters from thesecond load to the first load if a voltage droop on the first load isdetected and the first load has a higher priority than the second load.If the second load subsequently experiences voltage droop, controlapparatus 718 may reduce the power state of the second load until thevoltage droop on the second load is no longer detected.

In another example, both loads 714-716 may experience voltage droop ifthe power states of loads 714-716 are higher than can be accommodated bythe subsets of power converters 702-710 coupled to loads 714-716. Tomanage such voltage droops, current surges, and/or power overages,control apparatus 718 may reduce the power states of both loads 714-716until the voltage droop is no longer detected on both loads 714-716.Alternatively, control apparatus 718 may prioritize the driving of afirst load over a second load by increasing the number of powerconverters coupled to the first load and reducing the power state of thesecond load until the voltage droop is no longer detected on both loads714-716. Such prioritization may occur when the power demands of oneload must be met to satisfy certain system needs, such as powering ofcritical system components in the load. Finally, control apparatus 718may reduce the power states of both loads 714-716 while diverting one ormore power converters from one load to another until the voltage droopis no longer detected on both loads 714-716.

The MIMO power-delivery systems described above may further beconfigured to operate in a “tied” configuration that combines multiplepower converters into a single output that is used to power multipleloads in a portable electronic device. As shown in FIG. 8A, the outputsof a number of power converters 802-806 may be coupled to two or moreloads 814-816 through a switching assembly 812. A software and/orhardware control apparatus 818 executing within load 814 may be used togenerate control signals for switching assembly 812 to configure thecoupling of power converters 802-806 to loads 814-816 through switchingassembly 812.

In particular, the output of power converter 802 may be coupled directlyto load 814, and the output of power converter 806 may be coupleddirectly to load 816. Switching assembly 812 may include two switches808-810 that collectively couple the output of power converter 804 toone or both loads 814-816. For example, switch 808 may be closed tocouple power converter 804 to load 814, switch 810 may be closed tocouple power converter 804 to load 816, and both switches 808-810 may beclosed to couple all power converters 802-806 to both loads 814-816.

An alternative implementation of the “tied” configuration may beprovided by the MIMO power-delivery system of FIG. 8B. As with thepower-delivery system of FIG. 8A, the power-delivery system of FIG. 8Bincludes three power converters 802-806 that can be coupled to two loads814-816. The output of power converter 802 may be coupled directly toload 814, and the output of power converter 806 may be coupled directlyto load 816. Switching assembly 812 include a first switch 820 thatcouples the output of power converter 804 to either load 814-816, aswell as a second switch 822 that can be closed to “tie” the output ofall power converters 802-806 to both loads 814-816, independently of thestate of switch 820. Control apparatus 818 includes a switch control 824that generates a control signal for switch 820 and a tie control 826that generates a control signal for switch 822.

During power-state-based control of the power-delivery system, controlapparatus 818 may monitor the power demand of each load 814-816 todetermine the configuration of the power-delivery system. When the powerstate of each load 814-816 is below a pre-specified threshold, controlapparatus 818 may configure switching assembly 812 to power loads814-816 separately. When the power state of either load exceeds thecorresponding threshold, control apparatus 818 may operate thepower-delivery system in the “tied” configuration so that the outputs ofall power converters 802-806 are tied to the inputs of both loads814-816. The “tied” configuration may increase the peak current suppliedto multiple loads when one of the loads demands higher current than canbe supplied by the corresponding dedicated power converter(s).

For example, load 814 may be associated with a first numeric thresholdM, and load 816 may be associated with a second numeric threshold N,which may be the same or different from M. When the power states ofloads 814-816 are lower than M and N, respectively, control apparatus818 may generate control signals for switching assembly 812 so that eachload 814-816 is powered separately by the corresponding dedicated powerconverter 802 and 806. When the power state of load 814 is greater thanM and/or the power state of load 816 is greater than N, the power supplyvoltage of the higher power state is selected, and switching assembly812 are configured by control apparatus 818 to tie all outputs of powerconverters 802-806 to all inputs of loads 814-816.

Thus, the power-delivery system in the “tied” configuration effectivelybecomes a single-output power supply that is connected to all loads814-816. In the “tied” configuration, loads 814-816 may share power atfiner levels of granularity than discrete power levels of individualpower converters. For example, three 1 W converters that may be splitbetween loads 814-816 in a 2-1 configuration may be shared by loads814-816 so that each load receives 1.5 W or one load receives 1.2 W andthe other load receives 1.8 W. Such sharing of combined power bymultiple loads 814-816 may be based on the power draw and/or demand ofeach load.

The “tied” configuration may also be applied to the MIMO power-deliverysystems described above that continuously switch between driving loadsbased on error signals of the loads. Using the power-delivery system ofFIG. 5A as an example, if the power state of one or both loads 508-510exceeds the power-delivery capabilities of the corresponding dedicatedregulators 502 and 504, the outputs of all three regulators 502-506 maybe tied to supply power to both loads 508-510. When the power consumedby both loads 508-510 drops below the maximum power that can be suppliedby the corresponding dedicated regulators 502 and 504, thepower-delivery system may revert to coupling high-efficiency regulator506 to the load from loads 508-510 with the largest error signal.

Those skilled in the art will appreciate that the power-delivery systemsof FIGS. 7A-7B and 8A-8B may be adapted to different types, numbers, andconfigurations of power converters (e.g., power converters 702-710 and802-806), loads (e.g., loads 714-716 and 814-816), and switchingmechanisms (e.g., switching assemblies 712 and 812 and switches 808-810and 820-822). For example, different combinations of high-efficiencyconverter, high-power converters, and/or other types of power convertersmay be coupled to different numbers or types of loads in various sharedand/or dedicated configurations to optimize for power delivery in aportable electronic device. Similarly, the types of power convertersand/or components in the power converters may be selected to accommodatedifferent sizes and/or power states of loads in the portable electronicdevice. Moreover, switches in switching assembly 712 and 812 may beselected and/or configured to couple the power converters to the loadsin different ways. Control apparatuses 718 and 818 may further beimplemented using hardware and/or software components to couple thepower converters to the loads through various types and arrangements ofswitching assemblies 712 and 812. Finally, the power-delivery policyused by control apparatus 718 to configure the power-delivery system maybe tailored to the power states of the loads, the power output of thepower converters, the number of loads, and/or the number of powerconverters.

FIG. 9 shows a flowchart illustrating the process of operating a powersupply in accordance with the disclosed embodiments. In one or moreembodiments, one or more of the steps may be omitted, repeated, and/orperformed in a different order. Accordingly, the specific arrangement ofsteps shown in FIG. 9 should not be construed as limiting the scope ofthe embodiments.

Initially, a power-delivery policy for the power supply and power statesof two or more loads coupled to two or more voltage regulators in thepower supply are obtained (operation 902). The power-delivery policy maybe tailored to the types and numbers of loads and/or power converters ina portable electronic device, as well as the power consumption and/orpower states of the loads. For example, the power-delivery policy mayspecify the configuring of the loads and/or the coupling of the loads tothe power converters based on the power consumption associated withdiscrete power states of the loads, the maximum power that can besupplied by the power converters, and/or the maximum power that can bedrawn from the loads.

Next, one or more control signals for the loads and/or a set ofswitching mechanisms that couple the loads to the outputs of the powerconverters is generated based on the power-delivery policy, powerstates, and/or voltage droops. More specifically, the control signalsmay be used to couple the loads to the outputs of the power convertersthrough the switching mechanisms based on an increase above a firstthreshold in the power state of a first load (operation 904). Forexample, the power state of the first load may increase from a givenrange of numbers to a higher range of numbers that is represented by thefirst threshold. In turn, the power consumption of the first load mayincrease from a first voltage associated with the lower power state thatis below the first threshold to a second voltage associated with thehigher power state that is above the first threshold.

When an increase in the power state of the first load falls below thefirst threshold, the existing configuration of the coupling of the loadsto the power converters through the switching mechanisms is maintained(operation 906). For example, the first threshold may represent a limitto the power that can be outputted by power converters that are alreadycoupled to the first load. As a result, a power state of the first loadthat remains below the first threshold may indicate that the increasedpower consumption of the first load can be accommodated by the powerconverters coupled to the first load. In turn, the configuration of theswitching mechanisms may be maintained to avert power consumptionassociated with unnecessarily moving the switching mechanisms into a newconfiguration.

When the power state of the first load increases above the threshold,the coupling of the power converters to the loads may be managed basedon the power state of a second load and a second threshold (operation908). As with the first threshold, the second threshold may represent alimit to the power that can be outputted by power converters that arecoupled to the second load. The first and second thresholds may thus becombined to manage the delivery of limited power from the powerconverters to loads that can demand more power than can be outputted bythe power converters.

If the power state of the second load is below the second threshold, acontrol signal is generated to increase the number of power converterscoupled to the first load (operation 910). For example, the controlsignal may configure the switching mechanisms to couple one or moreadditional power converters to the first load to accommodate the addedpower consumption associated with the increased power state. Because thepower state of the second load is below the second threshold, the secondload may not be impacted by the coupling of the additional powerconverters to the first load.

If the power state of the second load is above the second threshold, theexisting configuration of the coupling of the loads to the powerconverters through the switching mechanisms is maintained (operation906). For example, a power state of the second load above the secondthreshold may represent a power consumption of the second load thatcannot accommodate the coupling of additional power converters to thefirst load. As a result, the existing configuration of the switchingmechanisms may be maintained because reconfiguring the switchingmechanisms increases the power consumption of the power supply andwithout alleviating the power demands of both loads.

An increase in the power state of one or more loads to a point thatcannot be accommodated by the power converters in the power supply mayresult in an excessive voltage droop on the load(s) (operation 912) thatis optionally monitored to detect excess power demand in the load(s).For example, an increase in the power state of a load that is notaccommodated by coupling additional power converters to the load (e.g.,due to the use of the power converters by other loads) may produce avoltage droop on the load as the load demands more power than can beproduced by power converters coupled to the load. If no voltage droop isfound in any of the loads, the loads may continue to be driven(operation 916) based on the power states of the loads and thresholdsassociated with the power states (operations 902-910).

If an excessive voltage droop on a load is detected, a control signal isoptionally generated to change the coupling of one or more additionalpower converters from another load to the load and/or reduce the powerstate of the load (operation 914). For example, if the total power drawnby the loads is detected to exceed the maximum power that can besupplied by the power converters, the power state of one or more loadsmay be reduced until the total power drawn can be accommodated by thepower converters. One or more power converters may also be diverted froma first load to a second load if the power state of the second load hasincreased and/or the power state of the first load can be lowered untilthe first load no longer requires the power converter(s).

The loads may continue to be driven (operation 916) using the switchingmechanism(s) and power converter(s). If the loads are to be driven, thepower-delivery policy, power states, and voltage droops are obtained(operation 902) and used to generate control signals that configure thedelivery of power from the power converters to the loads and/or theconsumption of power by the loads (operations 904-914). Power deliveryto the loads through the power converters and switching mechanisms maycontinue until the power supply is no longer used to drive the loads.

FIGS. 10A-10B shows a flowchart illustrating the process of operating apower supply in accordance with the disclosed embodiments. Morespecifically, FIG. 10A shows the operation of a power supply with sharedand dedicated power converters, and FIG. 10B shows an exemplaryoperation of the power supply with two loads “Load0” and “Load1” andthree power converters “VR0,” “VR1,” and “VR2.” Power converter 802 maybe represented by “VR0,” power converter 806 may be represented by“VR1,” and power converter 804 may be represented by “VR2.” Load 814 maybe represented by “Load0,” and load 816 may be represented by “Load1.”The power supply of FIG. 10B may include the configuration of FIG. 8A or8B, in which power converter 804 is shared between two loads 814-816 andeach load 814-816 is coupled directly to its own dedicated powerconverter 802 and 806. In one or more embodiments, one or more of thesteps may be omitted, repeated, and/or performed in a different order.Accordingly, the specific arrangement of steps shown in FIGS. 10A-1Bshould not be construed as limiting the scope of the embodiments.

Initially, a shared power converter is coupled to one of two loads(operation 1002). In FIG. 10B, the shared power converter “VR2” may becoupled to “Load0” in step 1018 or to “Load1” in Step 1020. Next, thepower supply may be operated based on a comparison of the power state ofthe load coupled to the shared power converter to a threshold associatedwith a tied configuration (operation 1004) in the power supply. Eachload may be associated with a numeric and/or other threshold thatrepresents the highest power state that can be accommodated by one ormore dedicated power converters for the load and the shared powerconverter.

In other words, if the power drawn by the load is represented by“Load_x,” the maximum power that can be supplied by the dedicated powerconverter for the load is “VR_x,” and the maximum power that can besupplied by the shared power converter is “VR_shared,” the threshold maybe expressed by the following:Load_x>VR_x+VR_sharedAs shown in FIG. 10B, the threshold associated with the tiedconfiguration may be represented by steps 1022-1024, which follow steps1018-1020, respectively.

When the power state of the load exceeds the threshold, a control signalis generated to couple all power converters to all loads through theswitching mechanisms (operation 1006) in a tied configuration. In FIG.10B, the tied configuration is represented by step 1026 (e.g., “TiedMode”). For example, a power supply voltage associated with the highestpower state among the loads is selected as the output voltage of thepower converters, which is then used to power all loads coupled to thepower supply. In other words, the tied configuration may be used toeffectively combine the outputs of the power converters into a singleoutput that is used to supply power to all of the loads.

The tied configuration may also be triggered when the power states ofboth loads are above the maximum power that can be supplied by thecorresponding dedicated power converters (operation 1008). For example,if the power drawn by the two loads is represented by “Load_x” and“Load_y,” respectively, and the maximum power that can be supplied bythe corresponding dedicated power converters is represented by “VR_x”and “VR_y,” respectively, the tied configuration may be triggered whenthe following expression is met:Load_x>VR_x AND Load_y>VR_yIf neither of the above conditions in operations 1004 or 1008 is met,the power supply is not operated in the tied configuration. Thecondition associated with the power states of both loads exceeding themaximum power that can be supplied by the corresponding dedicatedconverters is shown in steps 1028-1034 in FIG. 10B.

After the power supply enters the tied configuration (operation 1006),the power supply may be kept in the tied configuration until the powerstate of one load falls below the threshold associated with the tiedconfiguration and the power state of the other load falls below themaximum power that can be delivered by the corresponding dedicated powerconverter (operation 1012). Using the above representations of powerdrawn by the loads and the maximum power that can be supplied by thepower converters, the power supply may exit the tied configuration whenthe following expression is met:(Load_x<VR_x+VR_shared AND Load_y<VR_y)OR(Load_y<VR_y+VR_shared AND Load_x<VR_x)Thresholds that trigger the exit of the power supply from the tiedconfiguration are shown in steps 1036-1038 of FIG. 10B.

To exit the tied configuration, the shared power converter may becoupled to the load with the higher power requirement (operation 1014).For example, the shared power converter may be coupled to the load withthe power state that falls below the threshold associated with the tiedconfiguration but not below the maximum power that can be delivered bythe corresponding dedicated power converter. On the other hand, if thepower states of both loads fall below the maximum power that can besupplied by the corresponding dedicated power converters, the sharedpower converter may be coupled to the load with the power requirementthat is closer to the maximum power of the corresponding dedicated powerconverter. As shown in FIG. 10B, step 1018 is performed when thecondition of step 1036 is met, and step 1020 is performed when thecondition of step 1038 is met.

If the power supply is not operated in the tied configuration (e.g., ifneither of the conditions in operations 1004 or 1008 is met), the sharedpower converter may continue to be coupled to the existing load(operation 1002) until the power state of the load falls below themaximum power of the corresponding dedicated power converter and thepower state of the other load increases above the maximum power of theother corresponding dedicated power converter (operation 1010). Forexample, the power requirements of the existing load may be met by thededicated power converter for the load, while the current drawn by theother load may be higher than the current that can be delivered by oneor more other dedicated power converters for the other load.

In turn, the condition of operation 1010 may be detected as a voltagedroop on the other load. Using the above representations of power drawnby the loads and the maximum power that can be supplied by the powerconverters, the power state of the existing load “x” may fall below themaximum power of the corresponding dedicated power converter and thepower state of the other load “y” may increase above the maximum powerof the other corresponding dedicated power converter when the followingexpression is met:Load_x<VR_x AND Load_y>VR_yThe condition of operation 1010 in FIG. 10A may be expressed using steps1040-1046 in FIG. 10B.

When the power state of the load falls below the maximum power of thecorresponding dedicated power converter and the power state of the otherload increases above the maximum power of the other correspondingdedicated power converter, the shared power converter is coupled to theload with the higher power requirement (operation 1014). Put anotherway, the coupling of the shared power converter is changed from the loadin operation 1002 to the other load in operation 1014 to meet the powerrequirements of the other load when the condition in operation 1010 ismet. In FIG. 10B, step 1018 is performed if the conditions in steps1044-1046 are both true, and step 1020 is performed if the conditions insteps 1040-1042 are both true.

The loads may continue to be driven (operation 1016) using the switchingmechanism(s) and power converters. If the loads are to be driven, theshared power converter may be coupled to either load or coupled to bothloads in the tied configuration based on the power states of the loads(operations 1004-1014). Power delivery to the loads through the powerconverters and switching mechanisms may continue until the power supplyis no longer used to drive the loads.

The above-described power-delivery system can generally be used in anytype of electronic device. For example, FIG. 11 illustrates a portableelectronic device 1100 which includes a processor 1102, a memory 1104and a display 1108, which are all powered by a power supply 1106.Portable electronic device 1100 may correspond to a laptop computer,tablet computer, mobile phone, PDA, portable media player, digitalcamera, and/or other type of battery-powered electronic device. Powersupply 1106 may include one or more power converters and one or moreswitching mechanisms disposed between the output(s) of the powerconverter(s) and two or more loads. Power supply 1106 may also include acontrol circuit that obtains two or more error signals for the loads anduses the switching mechanism(s) to couple the load with a largest errorsignal from the two or more error signals to the output(s). The controlcircuit may also use the absolute value of the largest error signal tocontrol the output current(s) of the power converter(s).

Portable electronic device 1100 may also include a software-basedcontrol apparatus that obtains power states and voltage droops of theloads and a power-delivery policy for power supply 1106. Next, thecontrol apparatus may generate one or more control signals for the setof switching mechanisms to configure a coupling of the loads to two ormore power converters in power supply 1106 through a set of switchingmechanisms based on the power states, voltage droops, and/orpower-delivery policy.

The foregoing descriptions of various embodiments have been presentedonly for purposes of illustration and description. They are not intendedto be exhaustive or to limit the present invention to the formsdisclosed. Accordingly, many modifications and variations will beapparent to practitioners skilled in the art. Additionally, the abovedisclosure is not intended to limit the present invention.

What is claimed is:
 1. A method for operating a power supply,comprising: obtaining two or more error signals for two or more loadscoupled to a first output of a first power converter via a firstswitching mechanism, wherein each error signal from the two or moreerror signals represents a difference between a load voltage of a loadfrom the two or more loads and a first reference voltage for the loadfrom a first set of reference voltages for driving the two or more loadsusing the first power converter; and using the first switching mechanismto couple the load with a largest error signal from the two or moreerror signals to the first output.
 2. The method of claim 1, furthercomprising: generating a control signal for controlling an outputcurrent of the first power converter using at least one of: a largestvalue of a half-wave-rectified error signal from the two or more errorsignals; a sum of positive error signals from the two or more errorsignals; and an on-duration of a logical disjunction signal generatedfrom the two or more error signals.
 3. The method of claim 2, whereinthe output current is proportional to the control signal.
 4. The methodof claim 1, further comprising: uncoupling the first power converterfrom the two or more loads upon detecting a higher load voltage for eachload from the two or more loads than the first reference voltage fordriving the load from the two or more loads.
 5. The method of claim 1,further comprising: upon detecting a lower load voltage of the load thana second reference voltage for the load from a second set of referencevoltages for driving the two or more loads using a second powerconverter, engaging the second power converter to supplement the lowerload voltage with an output voltage from a second output of the secondpower converter.
 6. The method of claim 5, further comprising: using asecond switching mechanism disposed between the second output and thetwo or more loads to couple the load with the largest error signal tothe second output.
 7. The method of claim 6, wherein the first powerconverter has a higher efficiency than the second power converter, andwherein the second power converter has a higher power than the firstpower converter.
 8. The method of claim 7, wherein a first switchingfrequency is used by the first switching mechanism to couple the loadwith the largest error signal to the first output, and wherein a secondswitching frequency that is higher than the first switching frequency isused by the second switching mechanism to couple the load with thelargest error signal to the second output.
 9. The method of claim 7,wherein the first reference voltage for the load is higher than thesecond reference voltage for the load.
 10. The method of claim 1,wherein the two or more error signals comprise two or more requestsignals obtained from two or more comparators.
 11. The method of claim10, wherein using the first switching mechanism to couple the load withthe largest error signal to the first output comprises: coupling thefirst output to the load associated with a comparator from the two ormore comparators that first asserts a request signal representing alower load voltage for the load than the reference voltage for the load;and maintaining coupling of the first output to the load for a minimumpre-specified time.
 12. A power supply, comprising: a first powerconverter with a first output; a first switching mechanism disposedbetween the first output and two or more loads; and a control circuitconfigured to: obtain two or more error signals for the two or moreloads, wherein each error signal from the two or more error signalsrepresents a difference between a load voltage of a load from the two ormore loads and a first reference voltage for the load from a first setof reference voltages for driving the two or more loads using the firstpower converter; and use the first switching mechanism to couple theload with a largest error signal from the two or more error signals tothe first output.
 13. The power supply of claim 12, further comprising:a second power converter with a second output for driving at least oneof the two or more loads, wherein upon detecting a lower load voltage ofthe load than a second reference voltage for the load from a second setof reference voltages for driving the two or more loads using the secondpower converter, the control circuit is further configured to engage thesecond power converter to supplement the lower load voltage with anoutput voltage from the second output.
 14. The power supply of claim 13,further comprising: a second switching mechanism disposed between thesecond output and the two or more loads, wherein the control circuit isfurther configured to use the second switching mechanism to couple theload with the largest error signal to the second output.
 15. The powersupply of claim 14, wherein the control circuit comprises: a firstsub-circuit configured to control the first power converter and thefirst switching mechanism; and a second sub-circuit configured tocontrol the second power converter and the second switching mechanism.16. The power supply of claim 13, wherein the first power converter hasa higher efficiency than the second power converter, and wherein thesecond power converter has a higher power than the first powerconverter.
 17. The power supply of claim 13, wherein the first referencevoltage for the load is higher than the second reference voltage for theload.
 18. The power supply of claim 12, wherein the control circuit isfurther configured to: generate a control signal for controlling anoutput current of the first power converter using at least one of: alargest value of a half-wave-rectified error signal from the two or moreerror signals; a sum of positive error signals from the two or moreerror signals; and an on-duration of a logical disjunction signalgenerated from the two or more error signals.
 19. The power supply ofclaim 18, wherein the output current is proportional to the controlsignal.
 20. The power supply of claim 12, wherein the two or more errorsignals comprise two or more request signals obtained from two or morecomparators.
 21. A portable electronic device, comprising: a set ofcomponents; and a power supply configured to supply power to thecomponents, wherein the power supply comprises: a first power converterwith a first output; a first switching mechanism disposed between thefirst output and two or more loads; and a control circuit configured to:obtain two or more error signals for the two or more loads, wherein eacherror signal from the two or more error signals represents a differencebetween a load voltage of a load from the two or more loads and a firstreference voltage for the load from a first set of reference voltagesfor driving the two or more loads using the first power converter; anduse the first switching mechanism to couple the load with a largesterror signal from the two or more error signals to the first output. 22.The portable electronic device of claim 21, wherein the power supplyfurther comprises: a second power converter with a second output fordriving at least one of the two or more loads, wherein upon detecting alower load voltage of the load than a second reference voltage for theload from a second set of reference voltages for driving the two or moreloads using the second power converter, the control circuit is furtherconfigured to engage the second power converter to supplement the lowerload voltage with an output voltage from the second output.
 23. Theportable electronic device of claim 22, wherein the power supply furthercomprises: a second switching mechanism disposed between the secondoutput and the two or more loads, wherein the control circuit is furtherconfigured to use the second switching mechanism to couple the load withthe largest error signal to the second output.
 24. The portableelectronic device of claim 22, wherein the control circuit is furtherconfigured to: upon detecting an increase above a threshold in a powerstate of a load in the two or more loads, generating a control signal tocouple all of the first and second power converters to all of the two ormore loads through the first and second switching mechanisms.